This invention was made with government support under Contract No.: DAAJ09-91-C-A004 awarded by the Department of the Army. The government therefore has certain rights in this invention.
The present invention relates to a sensor alignment device, and more particularly to a compact self-contained portable apparatus which utilizes the missile target acquisition capability for effective seeker alignment calibration.
In many modern weapon systems, a seeker is movably mounted to sense the presence of a target. The seeker aligns itself with the target to generate signals which are used to direct the flight of the system to the target. To be fully adaptable and effective, however, the alignment of the seeker with the weapon system must be assured to prevent aiming errors during operation. In some instances inherent alignment errors due to manufacturing, storage or handling may compromise the seeker alignment.
Currently, alignment or boresighting of a seeker requires a distant target and extensive infrared signal exposure. It is desirable, therefore, to provide a compact self-contained portable apparatus and method which utilizes the missile target acquisition capabilities to achieve effective alignment.
The alignment device according to the present invention mounts to a missile system such that the view of a missile seeker is limited to a first and second limited field of view by a first aperture and a second aperture. The first aperture is preferably located along the missile centerline at zero degrees azimuth and zero degrees elevation. The second aperture is located at a predetermined position at an outermost field of view of the seeker which corresponds to seeker roll alignment. By locating the apertures at predetermined positions relative to a known reference such as the missile centerline, inherent alignment errors of the seeker can be determined.
Once the alignment device is mounted to the missile system, an energy source emitting energy viewable by the seeker is located within the first limited field of view. The seeker searches until it reaches a steady state or xe2x80x9clocked-onxe2x80x9d position. Once the seeker has locked-on to the energy source in the first limited field of view, the pointing angle of the seeker can be read by a measurement device communicating with the missile controller.
Any pointing angle read by the measurement device which differs from the known position defined by the alignment device, represents a displacement error of the seeker. Appropriate corrective calibration is then applied to the missile controller such that the inherent azimuth and elevation errors are accounted for.
Once the inherent azimuth and elevation errors are accounted for, the seeker is commanded to slew toward the second aperture. The energy source is then located within the second limited field of view such that the seeker can view the energy source through the second aperture. As the second aperture is also located at a known position relative to the centerline, an error free seeker will have a pointing angle equal to the known position of the second aperture.
Any pointing angle observed by the measurement device which differs from the known position of the second aperture represents a roll displacement error of the seeker. Appropriate calibration is then applied to the controller such that the inherent roll errors are accounted for.
The corrective calibration is iterative and may be repeated until the desired accuracy is achieved. Moreover, additional apertures can be provided to further refine the seeker alignment at other positions relative to the known reference.
The present invention therefore provides a compact self-contained portable apparatus and method which utilizes the missile target acquisition capability for achieving effective seeker alignment.